The present invention relates generally to a process for drying foods under a reduced pressure, and more particularly it relates to such a process for the preparation of dried foods which may be rehydrated to the original condition in a short time and have a pleasantness of taste and texture substantially comparable to untreated foods and also to the dried food processed through said process.
A variety of foods, in Japan so-called instant foods, which may be rehydrated simply by the addition of hot water or like means has heretofore been developed and commercially supplied. Multifarious efforts have been paid to develop more improved techniques for drying foods. As the outcomes of such efforts, various drying processes have been proposed, the representative examples being the hot air drying process, the micro-wave drying process, the freeze-dry process, the drying process and the process for drying the foods under reduced pressure. A swelling-drying process has also been proposed, in which a food to be dried is exposed to a flow of superheated steam for a while followed by heating to dehydrate the same and then placing the dehydrated food in the atmosphere abruptly to form a swelled product.
However, the dried foods processed through any of the known processes are not satisfactory, particularly in the taste and texture thereof after restoration. It cannot be said that the foods dried and then restored, according to the known processes have a taste and texture substantially comparable to those prior to treatment, since the former are inferior to the later in that they have a lack of springiness, are hard at the center portions, and have lost inherent adhesiveness and deteriorated in stiffness.
A further disadvantage of the foods or snack foods prepared from the known dried foods is that they have unpleasant odors caused by the heating at the drying step, or the flavour and taste thereof are lost or deteriorated. The last mentioned disadvantage causes serious problems from the commercial view-point particularly when the snack or fast food products are those which are eaten for their fresh flavour or taste, for example fruit snack products.